Simple Bubble, Selection, Insertion & Count Sort Implementation in C++

bubble_selection_insertion_count__sort

void swap(int &a, int &b) {
    int temp = a;
    a = b;
    b = temp;
}

void showArray(int arr[], int size) {
    for(int i = 0; i < size; i++) {
        cout << arr[i] << ", ";
    }
    cout << endl;
}

void bubbleSort(int arr[], int size) {
    for(int i = 0; i < size - 1; i++) {
        for(int j = 0; j < size - 1; j++) {
            if(arr[j] > arr[j + 1]) {
                swap(arr[j], arr[j + 1]);
            }
        }
    }
}

void selectionSort(int arr[], int size) {
    for(int i = 0; i < size - 1; i++) {
        for(int j = i + 1; j < size; j++) {
            if(arr[i] > arr[j]) {
                swap(arr[i], arr[j]);
            }
        }
    }
}

void insertionSort(int arr[], int size) {
    for(int i = 1; i < size; i++) {
        for(int j = i; j >= 1; j--) {
            if(arr[j] < arr[j - 1]) {
                swap(arr[j], arr[j - 1]);
            } else break;
        }
    }
}

void countSort(int arr[],int size) {
    int k = 0;
    int *arr = new int[size];
    for(int i = 1; i <= size; i++) {
        if(arr[i] > k) k = arr[i];
    } 
    int arr_index[k], output[size];
    for(int i = 0; i < k+1; i++) arr_index[i] = 0;
    for(int j = 1; j <= size; j++) arr_index[arr[j]]++;
    for(int i = 1; i <= k; i++) arr_index[i] += arr_index[i-1];
    for(int j = size; j >= 1; j--) {
        output[arr_index[arr[j]]] = arr[j];
        arr_index[arr[j]]--;
    }
}

int main() {
    int arr[] = {45,23,35,422,51,74,755,154,1,22,10};
    int size = sizeof(arr) / sizeof(int);
    showArray(arr, size);
    //sort function here
    showArray(arr, size);
    return 0;
}